A modified glassy carbon electrode has been constructed using a 4'-(4-carboxyphenyI)-2, 2': 6', 2"terpyridine(1, 10-phenanthroline)chloride ruthenium (II) tetrafluoroborate complex along with multiwalled carbon nanotubes and nation. The synthesized composite has been characterized using scanning electron microscopy, Transmission electron microscopy, and UV-Visible spectroscopy and IR spectroscopy. Electrochemical behaviour and stability of modified electrode has been investigated by cyclic voltammetry. Electrocatalytic activity of the modified electrode was investigated for the oxidation of phenyl hydrazine in 0.1 M phosphate buffer solution of pH 7.4. We observed Ruthenium complex/MWCNTs/ionomer composite has better electrochemistry, electrical properties and firm adhesion of the material with homogeneous dispersion at the electrode surface. The modified electrode showed electro-catalytic response to the oxidation of phenyl hydrazine at the potential of 600 mV. The linear range and detection limit for the detection of phenyl hydrazine in the optimum condition was found to be 5 x 10(-6) to 0.2 x 10(-3) M and 0.15 mu M respectively. The modified electrode also exhibited several attractive features such as simple preparation, fast response, good stability and repeatability. (C) 2012 Elsevier Ltd. All rights reserved.